8-Benzyloxy-6-ethoxycarbonyl-2,3-dimethylimidazo[1,2-a]pyridine → 6-Ethoxycarbonyl-8-hydroxy-2,3-dimethyl-5,6,7,8-tetrahydroimidazo[1,2-a]pyridine

HRID 723404Notes

Reaction equation

HRID 723404 reaction equation
C([O:8][C:9]1[C:10]2[N:11]([C:20]([CH3:24])=[C:21]([CH3:23])[N:22]=2)[CH:12]=[C:13]([C:15]([O:17][CH2:18][CH3:19])=[O:16])[CH:14]=1)C1C=CC=CC=1>C(O)C.[Pd]>[CH2:18]([O:17][C:15]([CH:13]1[CH2:12][N:11]2[C:20]([CH3:24])=[C:21]([CH3:23])[N:22]=[C:10]2[CH:9]([OH:8])[CH2:14]1)=[O:16])[CH3:19]

Participants

4

Reactant 1

HCID 121060828-Benzyloxy-6-ethoxycarbonyl-2,3-dimethylimidazo[1,2-a]pyridine

Product 1

HCID 121060846-Ethoxycarbonyl-8-hydroxy-2,3-dimethyl-5,6,7,8-tetrahydroimidazo[1,2-a]pyridineYield 14.5%

Reagents, catalysts & solvents 2

HCID 23938PalladiumCatalystHCID 702EthanolSolvent

Procedure

3 g of 8-benzyloxy-6-ethoxycarbonyl-2,3-dimethylimidazo[1,2-a]pyridine, suspended in 50 ml of ethanol, are treated with 0.5 g of 10% strength palladium/activated carbon and hydrogenated under a hydrogen pressure of 50 bar for 20 hours at an oil bath temperature of 75° C. After cooling, the catalyst is filtered off, the filtrate is concentrated to 1/5 of the volume in vacuo and the colourless precipitate formed here is filtered off. The filtrate of the precipitate is concentrated to dryness and chromatographed on silica gel (eluent: methylene chloride/methanol 100/3). 0.32 g of 6-ethoxycarbonyl-8-hydroxy-2,3-dimethyl-5,6,7,8-tetrahydroimidazo[1,2-a]pyridine is obtained. For conversion into the title compound, it is dissolved in chloroform, treated with 1.6 g of manganese dioxide and stirred at room temperature for 20 h. The precipitate is then filtered off, the filtrate is concentrated to dryness in vacuo and the residue obtained is purified on silica gel (eluent: methylene chloride/methanol 13/1). 0.2 g of the title compound of melting point 138–40° C. (diethyl ether) is obtained.

Workup

  1. customfor 20 hours
  2. customtemperature of 75° C
  3. temperatureAfter cooling
  4. filtrationthe catalyst is filtered off
  5. concentrationthe filtrate is concentrated to 1/5 of the volume in vacuo
  6. customthe colourless precipitate formed here
  7. filtrationis filtered off
  8. concentrationThe filtrate of the precipitate is concentrated to dryness
  9. customchromatographed on silica gel (eluent: methylene chloride/methanol 100/3)

Sources & evidence

ORD record
ord-e09a08d31bad4b74ad46a0cd54b5e1aa
Source dataset
uspto-grants-2006_11
Patent number
US07141567B2

Reaction notes

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